carbon paper

A thin paper coated with carbon black or some
other coloring matter in a vehicle of wax or an
oil-soluble substance and used for making
duplicate copies. It is sometimes used by
bookbinders to produce a dark color on a
bookbinding approximating blind tooling. Carbon
paper is also used for making paper pattern
layouts prior to lettering, and when the leather
does not darken uniformly with water. Size must
first be applied, otherwise the carbon will rub
off.